Reference:Layered Textures - Revision history

Clipka: canonicalize some version numbers

2021-06-09T14:51:16Z

canonicalize some version numbers

Jholsenback: 1 revision: Reference Migration Initial Load

2012-03-15T19:07:21Z

1 revision: Reference Migration Initial Load

Jholsenback: 1 revision: Initial Load (TF)

2012-03-11T22:27:52Z

1 revision: Initial Load (TF)

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[[Category:Textures]]
[[Category:Object Modifiers]]
It is possible to create a variety of special effects using layered
textures. A layered texture consists of several textures that are partially
transparent and are laid one on top of the other to create a more complex
texture. The different texture layers show through the transparent portions
to create the appearance of one texture that is a combination of several
textures.

You create layered textures by listing two or more textures one right after
the other. The last texture listed will be the top layer, the first one
listed will be the bottom layer. All textures in a layered texture other than
the bottom layer should have some transparency. For example:
<pre>
object {
My_Object
texture {T1} // the bottom layer
texture {T2} // a semi-transparent layer
texture {T3} // the top semi-transparent layer
}
</pre>

In this example T2 shows only where T3 is transparent and T1 shows only
where T2 and T3 are transparent.

The color of underlying layers is filtered by upper layers but the results
do not look exactly like a series of transparent surfaces. If you had a stack
of surfaces with the textures applied to each, the light would be filtered
twice: once on the way in as the lower layers are illuminated by filtered
light and once on the way out. Layered textures do not filter the
illumination on the way in. Other parts of the lighting calculations work
differently as well. The results look great and allow for fantastic looking
textures but they are simply different from multiple surfaces. See <code>
stones.inc</code> in the standard include files directory for some
magnificent layered textures.
Note: In versions predating POV-Ray 3.5, <code>filter</code> used to work the same
as <code>transmit</code> in layered textures. It has been changed to work as filter should. This can change the appearance of "pre 3.5" textures a lot. The <code>#version</code> directive can be used to get the "pre 3.5" behavior.
Note: Layered textures must use the <code>texture</code> wrapped around any pigment, normal or finish statements. Do not use multiple pigment, normal or finish statements without putting them inside the texture statement.

Layered textures may be declared. For example
<pre>
#declare Layered_Examp =
texture {T1}
texture {T2}
texture {T3}
</pre>

may be invoked as follows:
<pre>
object {
My_Object
texture {
Layer_Examp
// Any pigment, normal or finish here
// modifies the bottom layer only.
}
}
</pre>

Note: No macros are allowed in layered textures. The problem is that if a macro would contain a declare the parser could no longer guess that two or more texture identifiers are supposed to belong to the layered texture and not some other declare.

If you wish to use a layered texture in a block pattern, such as <code>
checker</code>, <code>hexagon</code>, or <code>brick</code>, or in a <code>
material_map</code>, you must declare it first and then reference it inside a
single texture statement. A patterned texture cannot be used as a layer in a
layered texture however you may use layered textures as any of the textures
contained within a patterned texture.

@@ Line 34: / Line 34: @@
 stones.inc</code> in the standard include files directory for some
 magnificent layered textures.</p>
-<p class="Note"><strong>Note:</strong> In versions predating POV-Ray 3.5, <code>filter</code> used to work the same
+<p class="Note"><strong>Note:</strong> In versions predating POV-Ray v3.5, <code>filter</code> used to work the same
-as <code>transmit</code> in layered textures. It has been changed to work as filter should. This can change the appearance of &quot;pre 3.5&quot; textures a lot. The <code>#version</code> directive can be used to get the &quot;pre 3.5&quot; behavior.</p>
+as <code>transmit</code> in layered textures. It has been changed to work as filter should. This can change the appearance of &quot;pre v3.5&quot; textures a lot. The <code>#version</code> directive can be used to get the &quot;pre v3.5&quot; behavior.</p>
 <p class="Note"><strong>Note:</strong> Layered textures must use the <code>texture</code> wrapped around any pigment, normal or finish statements. Do not use multiple pigment, normal or finish statements without putting them inside the texture statement.</p>
 <p>

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